Determination of sorption of seventy-five pharmaceuticals in sewage sludge

Abstract

Sorption of 75 active pharmaceutical ingredients (APIs) to three different types of sludge (primary sludge, secondary sludge with short and long sludge age respectively) were investigated. To obtain the sorption isotherms batch studies with the APIs mixture were performed in four nominal concentrations to water containing 1 g of sludge. The range of APIs concentrations was between ng L(-1) to μg L(-1) which are found in the wastewater effluents. Isotherms were obtained for approximately 45 of the APIs, providing distribution coefficients for linear (Kd), Freundlich (Kf) and Langmuir (KL) isotherms. Kd, Kf and KL ranging between 7.1×10(4) and 3.8×10(7), 1.1×10(-2) and 6.1×10(4) and 9.2×10(-3) and 1.1 L kg(-1), respectively. The obtained coefficients were applied to estimate the fraction of APIs in the water phase (see Abstract Graphic). For 37 of the 75 APIs, the predicted presence in the liquid phase was estimated to >80%. 24 APIs were estimated to be present in the liquid phase between 20 and 80%, and 14 APIs were found to have <20% presence in the liquid phase, i.e. high affinity towards sludge. Furthermore, the effect of pH at values 6, 7 and 8 was evaluated using one way ANOVA-test. A significant difference in Kds due to pH changes were found for 6 of the APIs (variation 10-20%).

Sorption of Perfluorinated Compounds onto different types of sewage sludge and assessment of its importance during wastewater treatment

“…Sludge preparation for sorption experiments was based on previous studies [Andersen et al, 2005, Hörsing et al, 2011. In brief, each type of sludge was washed three times using tap water, centrifuged to remove water soluble constituents and frozen at -18 ˚C for 24 h. Afterwards, sludge was gently freeze dried to preserve its structure, sterilized by heating at 103 ˚C for minimum 3 h and stored at 4 ˚C.…”

Occurrence of organic microcontaminants in the wastewater treatment process. A mini review

“…The concentrations of PPCPs detected in sewage sludge reflect their use in the society [40], although the influent wastewater is a better indicator, especially for hydrophilic and water soluble PPCPs that are not likely to be detected in sludge. According to Horsing et al [43], who studied the sorption of 75 common PPCPs, only 14 were found to have strong affinity with particles/sludge, whereas for 37 of them, more than 80% of their predicted occurrence would be in the liquid phase. In that study, pH was also identified as an important factor for the partition to the sludge.…”

Occurrence, distribution and potential affecting factors of antibiotics in sewage sludge of wastewater treatment plants in China

“…For some antibiotics, especially hydrophobic antibiotics, with their limited mobility and low biodegradation in the sludge, they are prone to adsorb onto sewage sludge and more stable than those in wastewater (Baquero et al, 2008;Cruz Moreno-Bondi et al, 2009;Zhou et al, 2009). Several studies have reported that many antibiotics in wastewater were considerably eliminated by sorption and transported to sewage sludge during sewage treatment (Batt et al, 2007;Beausse, 2004;Escher et al, 2011;Hörsing et al, 2011), indicating that sludge can serve as an important reservoir of antibiotics. Therefore, concentrations of antibiotics in sewage sludge can give an important indication on their pollution levels to some extent.…”